--- libmalloc/libmalloc-317.40.8/tests/perf_realloc.c
+++ libmalloc/libmalloc-166.251.2/tests/perf_realloc.c
@@ -38,6 +38,9 @@
 	dt_stat_time_t s = dt_stat_time_create(name);
 	dt_stat_set_variable((dt_stat_t)s, "size (bytes)", (unsigned int)size);
 	dt_stat_set_variable((dt_stat_t)s, "amount (bytes)", (int)amount);
+	// rdar://problem/40417821: disable thresholds for now.
+	//dt_stat_set_variable((dt_stat_t)s, kPCFailureThresholdPctVar,
+	//		PERFCHECK_THRESHOLD_PCT);
 	dt_stat_token now = dt_stat_time_begin(s);
 
 	for (;;) {